The specification relates to vehicular communication systems. In particular, the specification relates to a system and method for synchronously updating message rates to control communication congestion, where the message rates converge to weighted fair rates for different vehicles in a distributed manner.
Vehicles usually communicate with each other using Dedicated Short Range Communications (“DSRC”) channels specially designed for automotive use. It has been well known that congestion mitigation on the DSRC channels is one of the priorities in moving DSRC towards deployment. Existing message rate based congestion control strategies converge all the vehicles participating in congestion control to the same steady state message rates. In some scenarios, different steady message rates for different vehicles are desired. For example, ambulances and police cars engaged in emergency services travel at a much higher speed than private vehicles, and can be more prone to accidents. Therefore, practically it may be desirable that such vehicles transmit messages at a higher rate than the rates used by private vehicles. However, the existing message rate based congestion control strategies cannot achieve different steady message rates for different vehicles.